1) Do any rounds bind "get stuck" in the mag tube or can you load the gun to full capacity and cycle it fine. If the firearm works don't worry about it. The follower is made of light plastic and weighs very little so they don't usually drop out of the mag tube. I keep a short piece of broom handle around to push it out. After the follower become smooth because of moving in the tube it usually comes out easier.
2) The noise comes from inside the receiver or from the buttstock. If it come from the stock there may be something in it. Remove the recoil pad and look.